The St. Johns River as a water supply source

In many areas of the St. Johns River Water Management District, groundwater supplies have reached their sustainable limit or will reach sustainable limits in the near future. In those areas, traditional water source—fresh groundwater from the Floridan aquifer—will not be able to meet all future needs.

As required by the Florida Legislature in 1997 and as part of its water supply planning program, the district must identify potential water sources and investigate if and to what extent alternative water supply sources can be developed and used without harming the environment.

To meet future demands, water conservation will continue to play an important role, as may development of alternative water sources such as seawater, brackish (slightly salty) groundwater, reclaimed water and surface water. Increasing water conservation may defer the size, scope and timing of developing often expensive alternative water supply.

As part of its planning work, the district on Feb. 14, 2012, completed the four-year Water Supply Impact Study (WSIS) that evaluated the potential environmental effects of proposed withdrawals from the St. Johns and Ocklawaha rivers on the plants, animals and water resources of the St. Johns River.

The St. Johns River Water Supply Impact Study is the most comprehensive and scientifically rigorous analysis of the St. Johns River ever conducted. The study resulted in the development of tools that will help guide future decision-making on the potential environmental effects of proposed water withdrawals from the St. Johns and Ocklawaha rivers on the St. Johns River system. The state-of-the-art models and methodologies that resulted from the study will be used in consumptive use permitting, minimum flows and levels development, regional water projects and water supply planning.

The tools developed will be applied during the review process for any future river withdrawal permit applications. The amount of water that may ultimately be withdrawn will depend on the proposed location, design and timing of proposed withdrawals, as well as the numerous permitting criteria considered when permit applications are submitted.

The tools also can be used by the district, local governments, other agencies, and potentially with other river systems.

More than 70 scientists and engineers — a combination of district staff and many outside experts of international standing — contributed to this unparalleled analysis of the St. Johns River. The district engaged the nation’s most highly respected body of scientists, the National Academy of Sciences, to conduct an impartial peer review of the district’s project. Nine distinguished scholars from universities across the country actively participated on the peer review panel through the National Academy of Sciences/ National Research Council (NRC) and provided advice and recommendations to further the district’s scientific and technical work.

The study confirms the findings of earlier investigations indicating that the St. Johns River can be used as an alternative water supply source without causing significant harm to the environment. The study does not authorize river water withdrawals.